Monitoring strategy of COVID-19 vaccination in dialysis patients based on a multiplex immunodot method: The CovidDial study.

INTRODUCTION: COVID-19 vaccine was demonstrated to be effective in dialysis patients, but boosters are mandatory due to a rapid waning of anti-spike antibodies. A vaccination strategy based on immunologic response might be useful to maintain a favorable risk-benefit balance in this vulnerable population. METHODS: CoviDial is an observational prospective study enrolling 121 dialysis patients to receive a 3-dose mRNA-1273 vaccine according to a uniform schedule. At baseline, months 1, 3, 6, 9, and 12, anti-spike antibodies against four epitopes (S1, S2, ECD-S1 + S2, RBD) were monitored with a multiplex immunodot enzymatic assay. Potential correlation between initial serologic response and subsequent COVID-19 infection was then assessed. RESULTS: Overall, 96.2% and 96.8% of patients had anti-RBD antibodies at 3 and 12 months, respectively. All antibodies titers significantly decreased at month 6 compared to month 3. Booster vaccine induced a robust serologic response at month 9, but with a waning 3 months later, particularly for anti-S2 (37.2 ± 3.3 vs. 61.3 ± 3.0, p < 0.0001) and anti-S1 + S2 antibodies (68.4 ± 3.3 vs. 88.4 ± 2.3, p = 0.0015). Fifteen patients were later tested positive for SARS-CoV-2. At month 3, mean titers of anti-RBD, anti-S1 + S2, and anti-S2 antibodies were lower in the subsequent SARS-CoV-2 infected cohort (71.57 ± 9.01 vs. 85.79 ± 2.61, p = 0.0131; 41.07 ± 7.96 vs. 61.68 ± 3.56, p = 0.0237; 13.79 ± 5.03 vs. 39.70 ± 3.86, p = 0.0096; respectively). CONCLUSION: Three doses of mRNA-1273 vaccine induce a robust but time-limited immunologic response in dialysis patients. Lower anti-spike antibodies titers after initial vaccination are associated with a higher risk to subsequently contract SARS-CoV-2, even beyond 6 months.

Imported Malaria in Children: A Study Over an 11-Year Period in Brussels.

BACKGROUND: Malaria is a major global public health concern in endemic countries and imported childhood malaria is increasing in malaria non-endemic countries. METHODS: This was a retrospective case review of all laboratory-confirmed malaria cases in children 0-16 years admitted between 2009 and 2019 in 2 large university teaching Hospitals in Brussels. RESULTS: A total of 160 children with a median age of 6.8 years (range 5-191 months) were included. We identified 109 (68%) children living in Belgium who had acquired malaria during their visit to malaria-endemic countries to visiting friends and relatives (VFRs), 49 children (31%) visitors or newly installed migrants, and 2 Belgian tourists. Peak seasonal incidence occurred between August and September. Plasmodium falciparum was responsible for 89% of all malaria cases. Almost 80% of children living in Belgium visited a travel clinic for advice, but only one-third reported having taken the prophylaxis schedule according to the recommendations. Based on WHO criteria, 31 children (19.3%) developed severe malaria; most of the patients with severe malaria were VFR travelers and were significantly younger, had higher leukocytosis, had more thrombocytopenia, higher CRP, and lower natremia compared with patients with an uncomplicated course. All children recovered fully. CONCLUSIONS: Malaria is a significant cause of morbidity among returning travelers and newly arrived immigrants to Belgium. Most of the children had an uncomplicated disease course. Physicians should educate families about traveling to malaria-endemic areas to correct malaria preventive measures and prophylaxis.

Easy discrimination of hematogones from lymphoblasts in B-cell progenitor acute lymphoblastic leukemia patients using CD81/CD58 expression ratio.

INTRODUCTION: The discrimination of leukemia lymphoblasts (LB) in diagnosis and follow-up of B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) by multiparameter flow cytometry (MFC) may be difficult due to the presence of hematogones (HG). The aim of this study was to compare lymphoblasts of BCP-ALL and HG for the expression of the most discriminating antigens. METHODS: A total of 82 bone marrow samples (39 BCP-ALL and 43 patients with HG) were analyzed using MFC. Mean fluorescence intensity (MFI) was measured for ten markers commonly used in hematology laboratories: CD45, CD19, CD10, CD34, CD38, CD20, CD22, CD58, CD81, and CD123. Statistical comparison of the MFI between LB and HG was performed. The presence on LB of aberrant expression of myeloid and/or T-cell markers was also investigated. RESULTS: Qualitative pattern expression of antigens showed overexpression on LB of CD58, CD22, CD34, CD10 and underexpression of CD81, CD45, CD38 when compared to HG. Expression of CD123 was positive in 34% of BCP-ALL LB and always absent on HG. Aberrant antigen expression (myeloid and/or T-cell marker) including CD123 was observed in 58% of BCP-ALL patients. The use of a MFI antigen ratio of the most discriminating markers (CD81/CD58) (analysis of variance, P < 0.005) increased the distinction of LB versus HG with a high specificity and sensitivity as demonstrated by the use of ROC curve analysis (AUC of CD81/CD58: 0.995). CONCLUSION: We demonstrate in this study that routine use of the MFI antigen ratio (CD81/CD58) in addition to the MFC evaluation using WHO classical criteria appears to be an efficient approach to discriminate LB from HG.

Case Report: Delayed or Recurrent Plasmodium falciparum Malaria in Migrants: A Report of Three Cases with a Literature Review.

Emerging evidence indicates that migrants from Plasmodium falciparum endemic regions are at risk of delayed presentation of P. falciparum malaria. We report three cases of P. falciparum malaria occurring years after arrival in Europe. All patients were originally from Sub-Saharan Africa. Two subjects had controlled human immunodeficiency virus infection and one was a pregnant woman. We performed a literature review of all published cases of delayed presentation of P. falciparum in migrants and identified 32 additional cases. All cases but one originate from sub-Saharan Africa. There was a median time of 36 months between the last visit to a malaria-endemic country and clinical malaria (range: 3 months to 10 years). Pregnancy was the most frequently reported risk factor (11/35 or 31.4%). Parasitemia was ≤ 0.1% in 38% of cases (11/29 reported), and no death was reported. The underlying possible mechanisms for this delayed presentation in migrants from an endemic area probably include the persistence of submicroscopic parasitemia combined with decaying P. falciparum-specific immunity. Suspicion of P. falciparum delayed malaria should remain high in migrants, mainly from sub-Saharan Africa, even without a recent travel history, especially in those presenting risk factors for impaired parasite clearance or distinct immune responses such as pregnancy and HIV infection. In these patients, new prevention and screening strategies should be studied and blood safety policies adapted.

Urine iodide determination by ion-pair reversed-phase high performance liquid chromatography and pulsed amperometric detection.

A sensitive and specific ion-pair reversed-phase high performance liquid chromatography (HPLC) method for urinary iodine analysis is described. This method is based on pulsed amperometric detection (PAD) using a silver working electrode (HPLC-PAD), which improves peak shape, electrode stability as well as linearity and reproducibility. A two-step extraction process consisting of solid phase extraction (SPE) and liquid-liquid extraction with dichloromethane was added in order to improve sample purification which is essential with the use of PAD. Treated samples were eluted on a C18 column, using a phosphate buffer containing ion-pairing reagent tetrabutylammonium and 5% MeOH. The calibration standard curves were linear up to 500 µg/L and within-run and between-run coefficients of variation (CVs) were <6% with the quantification limit fixed at 6 µg/L. Accuracy, expressed as recovery, ranged from 94% to 104%. Comparison with the Technicon AutoAnalyzer acid digestion (AA) method resulted in a high correlation (r=0.9916). Due to a low quantification limit and high sample throughput, the proposed technique appears suitable for both epidemiological and clinical follow-up studies.